I have no brakes in my ford employer

Bench bleed a new master cylinder ten install. If you have ABS DO NOT change or empty. I know of no way to bench bleed it. The cylinder is probably 21 years old. There are rubber "O" rings inside the cylinder. The normal travel of the plunger never gets to the furthest end. Rust oftentimes forms at the ends. When the brakes are pumped to their furthest point (all the way to the floor) it can damage the rings. Bleed all the brakes until clear new fluid comes out of all wheel calipers. If finances permit, may want to consider changing pads and calipers..